Max showed a valuable point there. However, since your wood is preheated, you will have a wery similar effect to condensing hopper. In my experisnces, moisture is a performance killer specialy at low gas demand. You will never idle or highidle so you will get by better. I think if you dont burn greenwood you will be fine. If you do, some condensation will be required.
In general yes, the dryer the better, so guys condense out as much water/tar as possible. The thing is, running for so long and burning so much moist fuel, and condensing all the condensate from the heated hopper, you will end up wit enormous quantitys of tarry condensate you cant just spill out anywhere. I think its better to pass some water trugh the hearth, condense out in the gas cooler anddispose this clean condense out anywhere you want.

The process is a balancing act. The greatest gain is that the N2 has gone down to almost half of what it is in a single stage process. The increased H/CO ratio makes a faster burning process, still with no increase of CO2.

The result giving point here is the “enormous” heat returning cycle from the exit gas;
in a “1-stage” normal system almost all the drying and pyrolysing heat is “stolen” directly from the underlying blasted hearth. (by radiation and local vertical circulation)

It takes less hearth energy to crack superheated steam (available from the preheater process) than starting first to boil and to superheat water from cold wood.
And whole the pyrolysing heat demand.

With other words: The nozzle blasted heat extends better to crack more superheated steam, when there is no need to start from cold-wood-humidity.

The same principal (in a way) is the aim with the “plank” gasifier. But it can also condens a part of the silo wood humidity, not available (so far) in the Viking.

Im going to conserve as much heat as possible from the process for the pre heating of wood chips.
The first gasifier build is going to be a downdraft gasifier like I have shown in post 1, later as I learn more and get more experience I like to try to build a upstream gasifier like the Viking.
But to save time and not deviate from the original Ill build as close as possible to my first idea.
I already have multiple thermocouple sensors type K to see what is going on inside the gasifier, to measure inside the heart I need to find another type of sensor.

Yes they have, they use all available heat, instead of wasting it, to charcoal the fuel…

First stage is a “retort charcoaling system” , second part is a charcoal gasifier

At 15 to 20% moist content the system will run perfect, but at 50% , as they claim, no way …
If they work on their gasifier a bit more careful to reduce the huge co2 content they have now, i could believe the numbers.
The only way to do that is to install a condense catcher after the first stage and only use as much water from the moist possible, but never all…

To give you a number : from dry bamboo , in oven retort to charcoal, i have almost 2 kg liquid for every 5 kg bamboo…

I rely liked the performance they got from the Viking gasifier, and the duration of time they had it going non stop is unlike any I have seen before. The documentation of this gasifier is from a good university in Denmark and Im not going to despute that.

I think the most important things they report are the content of nitrogen, and hydtogen. Let’s suppose that the 50% m/c fuel is a mis statement. If the nitrogen and hydrogen contents are reported accurately, as seems so, they have something significant going on here?

The low amount nitrogen comes from the “first stage retort” it produces a “rich gas” no extra air injected.
2: the higher amount of hydrogen = equal to the enormous quantity of water in the gas + the higher amount of Co2

reduce the watercontent and then see the numbers going towards 35% CO and 20% Hydrogen and low CO2 (<3%)
Hydrogen per volume is less energetic then CO per volume, it needs the same quantity (+/-) air to combust
Yes the ignition timing is shorter but also need more attention to the cooling from the engine…

In the case of the Weiss gasifier, the numbers make it look as quenching the glowing charcoal

the shown temperature zones in their prospect are actual glowing if the numbers are correct.

Advice for copying the viking system ( my guess is this the real case scenario ) ; preheat the fuel up to 400ºC , extract the condensate before it enters the second stage… ( rotating valve ) , keep the heat in the fuel, drizzle the pre-heated fuel into a WK style gasifier unit underneath and enjoy…

My feeling is that Roger is going to build something that we all can learn from and benefit.

In the absence of materials and the freezing cold at the moment I have started to build the governing of the CHP build.
Im using a Siemens S7-300 PLC, a Phoenix contact analog input with 16 temperature sones termocouple type K and a distributed IO that has 16 digital inputs and 16 digital outputs for now.
I use PROFIBUS as communication between the units.

JO and Kristijan this is outdated equipment from where I work, we dont use profibus any more, these days its all about profinet (ordinary network for the industry).
As for cost you would think it is expensive but if you look up the newer S7 1200 PLCs they have come down in price compared to what it was some years a go.
A automated CHP needs a PLC.
Im also going to try something new for me and that is to use Labview to log temperatures and as a HMI, that means OPC server between the two systems.